Lithium ion secondary battery

Abstract

The purpose of the present invention is to provide a lithium ion secondary battery having excellent performance in output discharging and regenerative charging when charging and A discharging handle heavy loads equivalent to at least 10 C in hour rate. A lithium ion secondary battery having a cathode, an anode, a separator, lithium salt that supplies at least lithium ion, and nonaqueous electrolyte that includes said lithium salt which is characterized in that: the concentration of said lithium salt in said nonaqueous electrolyte of said lithium ion secondary battery is between 0.3 mol/liter and 3.0 mol/liter after conducting a 300 hours of cyclic test of charging and discharging on said lithium ion secondary battery, (in which charging and discharging condition is: a. 10 seconds of discharging with 10 C of hour rate (Rate), +b. 20 seconds of charging with 5 C of hour rate (Rate), +c. giving substantial absence of open circuit period).

What is claimed is:  
     
         1 . A lithium ion secondary battery having a cathode, an anode, a separator, a lithium salt that supplies at least lithium ion, and a nonaqueous electrolyte that includes said lithium salt ; wherein the concentration of said lithium salt in said nonaqueous electrolyte of said lithium ion secondary battery is between 0.3 mol/liter and 3.0 mol/liter after conducting a 300 hours of cyclic test of charging and discharging on said lithium ion secondary battery (in which charging and discharging condition is: a. 10 seconds of discharging with 10 C of hour rate (Rate), +b. 20 seconds of charging with 5 C of hour rate (Rate), +c. giving substantial absence of open circuit period).  
     
     
         2 . A lithium ion secondary battery according to  claim 1 , wherein a cyclic test of charging and discharging on said lithium ion secondary battery are 700 hours.  
     
     
         3 . A lithium ion secondary battery according to  claim 1 , wherein a cyclic test of charging and discharging on said lithium ion secondary battery are 1500 hours.  
     
     
         4 . A lithium ion secondary battery having a cathode, an anode, a separator, a lithium salt that supplies at least lithium ion, and a nonaqueous electrolyte that includes said lithium salt; wherein the concentration of said lithium salt in said nonaqueous electrolyte of said lithium ion secondary battery is between 0.3 mol/liter and 3.0 mol/liter after conducting a 700 hours of cyclic test of charging and discharging on said lithium ion secondary battery (in which charging and discharging condition is: a. 10 seconds of discharging with 10 C of hour rate (Rate), +b. 10 seconds of charging with 10 C of hour rate (Rate), +c. giving substantial absence of open circuit period).  
     
     
         5 . A lithium ion secondary battery having a cathode, an anode, a separator, a lithium salt that supplies at least lithium ion, and a nonaqueous electrolyte that includes said lithium salt; wherein the concentration of said lithium salt in said nonaqueous electrolyte of said lithium ion secondary battery is between 0.3 mol/liter and 3.0 mol/liter after conducting a 700 hours of cyclic test of charging and discharging on said lithium ion secondary battery (in which charging and discharging condition is: a. 20 seconds of discharging with 5 C of hour rate (Rate), +b. 10 seconds of charging with 10 C of hour rate (Rate), +c. giving substantial absence of open circuit period).  
     
     
         6 . A lithium ion secondary battery according to  claim 1 , wherein the concentration of said lithium salt in said nonaqueous electrolyte is between 0.5 mol/liter and 3.0 mol/liter.  
     
     
         7 . A lithium ion secondary battery according to  claim 1 , wherein a workable capacity of said cathode is between 0.30 mAh/cm 2  and 0.75 mAh/cm 2  for the unit area of cathode-to-anode facing.  
     
     
         8 . A lithium ion secondary battery according to  claim 1 , wherein a workable capacity of said anode is between 0.30 mAh/cm 2  and 0.75 mAh/cm 2  for the unit area of cathode-to-anode facing.